Thermochemical scarfing process



Nov. 5, 1957 P. THOMPSON ET AL ,2

THERMOCI-IEMICAL SCARFING PROCESS Original Filed Aug. 17, 1950 INVENTORS IVAN P. THOMPSON WILLIAM ALLMANG WILLIAM C.WEIDNER ML/ZJMQJ ATTO R N EY tates Patent Ofitice Patented Nov. 5, 1957 THERMOCHEMICAL SCARFING PROCESS Ivan P. Thompson, Elizabeth, William Allmang, Bloomfield, and William C. Weidner, Summit, N. J., assignors, by mesne assignments, to Union Carbide Corporation, a corporation of New York Original application August 17, 1950, Serial No. 179,904, now Patent No. 2,745,475, dated October 23, 1955. Divided and this application June 20, 1955, Serial No. 516,506

Claims. (Cl. 148-95 This invention relates to thermochemical scarfing processes, and more particularly to post-mixed preheat continuous slot processes for thermochemical oxy-acetylene metal removal.

The wide flat cutting oxygen streams heretofore employed have been confined between upper and lower surfaces of equal extent along the stream toward the work surface, and the post-mixed fuel gas orifices have been correspondingly located. To allow room for the lower surface and preheat orifices and clearance for the work, the upper surface has been located high above the work. In view of the acute angle of impingement, this condition has left the outside of the oxygen stream free to expand, and open to the air and consequent contamination. This condition has also kept the preheat orifices the same distance along the stream from the reaction zone, rendering difiicult the starting of the reaction.

The main object of the present invention is to extend the confining surface for the outside of the oxygen stream farther along the stream toward the reaction zone than the confining surface for the inside of the oxygen stream, for a distance greater than the space between the surfaces.

Another object of the present invention is to locate the outside preheat fuel gas orifices farther along the oxygen stream toward the reaction zone than the inside preheat fuel gas orifices, for a distance greater than the thickness of the oxygen stream.

According to the present invention a sheet-like stream of oxidizing gas is discharged onto a reaction zone extending across a metal body and at an acute angle of impingement to the work surface of said metal body, and the outside of said stream of oxidizing gas is confined smoothly and continuously farther along the stream toward the reaction zone for a distance greater than the thickness of said stream. Preferably transverse rows of jets of preheat fuel gas are projected against the outside of said stream, the row of jets projected against the outside of said stream being located nearer to the zone of reaction than the row of jets of preheat fuel gas projected against the inside of said stream for a distance along the stream greater than the thickness of said stream.

In the drawings:

Fig. 1 is a diagram of apparatus for carrying out the process according to the preferred embodiment of the present invention; and

Fig. 2 is a diagram illustrating a modification.

As shown in the drawing the oxidizing gas is projected in a Wide continuous stream S at an acute angle of impingement onto the reaction zone R, which extends transversely across the entire width of the work W. The stream is confined by an outer surface T and an inner surface B. The outer surface T extends smoothly and continuously forwardly along the stream S toward the reaction zone beyond the inner surface B for a distance greater than the thickness of the stream S. This extension of the outer surface T forms an overhanging lip L, the front edge of which is close to the horizontal projection of the front edge of the inner surface B.

An outer transverse row of jets of preheat fuel gas P is projected inwardly at an acute angle against the outside of the stream S beyond the front edge of the lip L, and an inner row of preheat fuel gas jets F is projected outwardly at an acute angle against the inside of the stream S beyond the front edge of the inner surface B. The outer preheat jets are thus located nearer along the stream to the zone of reaction than the inner preheat jets for a distance greater than the thickness of the stream.

The confining of the upper surface of the stream of oxidizing gas beyond the lower surface thereof and nearer to the reaction zone prevents the tendency of the gas to expand and escape, and also prevents contamination of the stream by outside air. In operation the stream of oxidizing gas tends to hug or cling to and follow the underside of the overhanging lip L, and so be projected in a straight line continuing onto the reaction zone with a decreased amount of turbulence.

The location of the outer preheat jets nearer to the reaction zone increases the heat transfer to and temperature rise of the reaction zone, greatly facilitating starting, and increasing the efiiciency of the reaction, because the hottest part of the preheat flame is brought nearer to the reaction zone. Also, the outer preheat flames themselves tend to confine the oxidizing gas stream and shield it from contamination.

The location of the inner preheat jets facilitates heat transfer to the stream of oxidizing gas, which arrives at the highly heated reaction zone in highly heated condition.

The process as shown in Fig. 1 is adapted to scarfing the top, bottom and sides of rectangular shapes, and also to the scarfing of rounds, as shown in Fig. 2, in which the stream S, the outer surface T and the inner surface B are conical, and the rows of preheat jets P and F are concentric circles.

This application is a division of our copending application Serial No. 179,904 filed August 17,, 1950, now Patent No. 2,745,475, granted October 23, 1955.

We claim:

1. In a process for thermochemically scarfing metal bodies, confining the inside and outside of a supply of oxidizing gas to form a stream of substantially uniform thickness, discharging said sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body and at an acute angle of impingement to the work surface of said metal body, and continuing the confinement of the outside of said stream of oxidizing gas smoothly and continuously farther along the stream toward the reaction zone than the inside of said stream for a distance greater than the thickness of the stream.

2. Process for thermochemically scarfing metal bodies, which comprises confining the inside and outside of a supply of oxidizing gas to form a stream of substantially uniform thickness, discharging said sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body and impinging at an oblique angle to the work surface of said metal body, continuing the confinement of the outside of said stream of oxidizing gas smoothly and continuously farther along the stream toward the reaction zone than the inside of said stream for a distance greater than the thickness of said stream, and applying heat to at least the outside of said stream beyond the confinement thereof on its way to said reaction zone.

3. In a process for thermochemically scarfing metal bodies, discharging a sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body and at an acute angle of impingement to the work surface of said metal body, and projecting transverse rows of jets of preheat fuel gas against said stream, the row of jets projected against the outside of said stream being located nearer along the stream toward the zone of reaction than the row of jets of preheat fuel gas projected against the inside of said stream for a distance along the stream greater than the thickness of said stream.

4. In a process for thermochemically scarfing metal bodies, discharging a sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body and at an acute angle of impingement to the work surface of said metal body, and confining said sheet-like stream of oxidizing gas between surfaces respectively nearer to and farther from said work surface, said farther surface extending smoothly and continuously forwardly and terminating in a front edge beyond the front edge of said nearer surface in overhanging relation thereto for a distance measured along said stream and greater than the spacing between said surfaces, to bring the front edge of said farther surface close to the horizontal projection of the front edge of said nearer surface.

5. In a process for thermochemically scarfing metal bodies, discharging a sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body and impinging at an oblique angle to the work surface of said metal body, confining said sheet-like stream of oxidizing gas between surfaces respectively nearer to and farther from said work surface, said farther surface extending smoothly and continuously forwardly and terminating in a front edge beyond the front edge of said nearear surface in overhanging relation thereto for a distance measured along said stream and greater than the distance between said surfaces, to bring the front edge of said farther surface close to the horizontal projection of the front edge of said nearer surface, and applying heat to the outside of said stream along a transverse line ahead of the front edge of said farther surface.

6. In a process for thermochemically scarfing metal bodies, discharging a sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body, and at an acute angle of impingement to the work surface of said body, confining said sheet-like stream of oxidizing gas between surfaces respectively nearer to and farther from said work surface, said farther surface extending smoothly and continuously forwardly and terminating in a front edge beyond the front edge of said nearer surface in overhanging relation thereto for a distance measured along said stream and greater than the spacing between said surfaces, to bring the front edge of said farther surface close to the horizontal projection of the front edge of said nearer surface, and discharging a row of preheat flames in a plane at an acute dihedral angle to said oxidizing gas stream toward said reaction zone from a row of orifices spaced along the oxygen stream ahead of the front edge of said lower surface.

7. In a process for thermochemically scarfing metal bodies, discharging a sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body, and at an acute angle of impingement to the work surface of said body, confining said sheet-like stream between surfaces respectively nearer to and farther from said work surface, said farther surface extending smoothly and continuously forwardly and terminating in a front edge beyond the front edge of said nearer surface in overhanging relation thereto for a distance measured along said stream and greater than the spacing between said surfaces, to bring the front edge of said farther surface close to the horizontal projection of the front edge of said nearer surface, discharging a row of inner preheat flames toward said reaction zone in a plane at an acute angle to the work surface from a row of orifices inside said nearer surface of said stream of oxidizing gas, and discharging a row of outer preheat flames toward said reaction zone in a plane at an acute angle to said stream of oxidizing gas from a row of orifices outside said stream of oxidizing gas and spaced therealong ahead of said row of inner preheat orifices.

8. In a process for thermochemically scarfing metal bodies, discharging a sheet-like stream of oxidizing gas onto a reaction zone extending across a metal body and at an acute angle of impingement to the Work surface of said metal body, and confining said sheet-like stream of oxidizing gas between surfaces respectively nearer to and farther from said work surface, said farther surface extending smoothly and continuously forwardly and terminating in a front edge beyond the front edge of said nearer surface in overhanging relation thereto for a distance measured along said stream and greater than the spacing between said surfaces, to bring the front edge of said farther surface close to the horizontal projection of the front edge of said nearer surface to confine said oxygen stream close to the Work surface and thereby impinge the stream of oxidizing gas directly onto the reaction zone, and projecting a plurality of fuel gas jets equidistant from said slot and in a line adjacent thereto toward said sheet-like stream of oxidizing gas.

9. Process for thermochemically scarfing metal bodies as claimed in claim 1 in which said sheet-like stream of oxidizing gas is conical.

10. Process for thermochemically scarfing metal bodies as claimed in claim 3 in which said rows of preheat fuel gas orifices are concentric circles.

References Cited in the file of this patent UNITED STATES PATENTS 2,277,472 Anderson Mar. 24, 1942 2,346,718 Anderson Apr. 18, 1944 2,532,103 Kiernan Nov. 28, 1950 

1. IN A PROCESS FOR THERMOCHEMICALLY SCARFING METAL BODIES, CONFINING THE INSIDE AND OUTSIDE OF A SUPPLY OF OXIDIZING GAS TO FORM A STREAM OF SUBSTANTIALLY UNIFORM THICKNESSS, DISCHARGING SAID SHEET-LIKE STREAM OF OXIDIZING GAS ONTO A REACTION ZONE EXTENDING ACROSS A METAL BODY AND AT AN ACUTE ANGLE OF IMPINGEMENT TO THE WORK SURFACE OF SAID METAL BODY, AND CONTINUING THE CONFINEMENT OF THE OUTSIDE OF SAID STREAM OF OXIDIZING GAS SMOOTHLY AND CONTINUOUSLY FARTHER ALONG THE STREAN TOWARD THE REACTION ZONE THAN THE INSIDE OF SAID STREAAM FOR A DISTANCE GREATER THAN THE THICKNESS OF THE STREAM. 